Dear Technicians,

One of our Office 365 user in my company was trying to send an email to one of our distribution groups with 12 users inside whose email accounts are all in on-premise database (Exchange 2010), and got a NDR back said "550 5.5.3 RESOLVER.ADR.RecipLimit; too many recipients". As the default recipients limitation for 365 accounts is 500, the user shouldn't get this kind of errors in the first place. I also checked the email flow in both 365 and on-premise, it seems that the email had been delivered to our on-premise Exchange 2010 server but then it could not be sent out with "Routing fail". Also, in on-premise Exchange 2010 server, the recipients limitation has been set as 20 in "Organization Configuration -> Hub Transport -> Global Settings -> Transport Settings". Another information is we recently updated Exchange 2010 with Rollup 1 to 5. May I please have your help about this? Thanks.

Yours faithfully,
Steven Liu

Raise the recipient limitation to 100 and see if the message goes through, then you'll have your answer.

Hi Ed,

Thanks for your reply.

It has been set to 20 (also I have tried to untick the setting which means no limitation at all) but the error message was still saying "This message wasn't delivered to anyone because there are too many recipients. The limit is 10. This message has 12 recipients."

Actually, the problem is, the error out regardless of our Exchange settings for some reason.

Hi Ed,

Thanks for your reply.

It has been set to 20 (also I have tried to untick the setting which means no limitation at all) but the error message was still saying "This message wasn't delivered to anyone because there are too many recipients. The limit is 10. This message has 12 recipients." Also, I am sure that a distribution group should be treated as one recipient in Exchange 2010, so the error message makes no sense.

Actually, the problem is, the error out regardless of our Exchange settings for some reason.

• Edited by Hang L 23 hours 56 minutes ago

Look in the properties of all connectors in the path and in the global transport settings to see if it's set lower somewhere.